ByHolbrook Mohr and Jeff Amy, Associated PressAugust 29, 2012

Boats are battered in the harbor as Hurricane Isaac passes through Pass Christian, Mississippi, August 29. The slow-moving but powerful Category 1 hurricane was felt along the Gulf Coast, threatening to flood towns in Mississippi and Louisiana with storm surges of up to 12 feet and top sustained winds up to 75 miles per hour.

Thousands of residents in south Mississippi remained without power, officials said.

Power outage totals in Mississippi rose. Coast Electric Power Association said about 14,000 customers were without power early Wednesday. Singing River Electric Power Association also reported about 1,500 customers with the lights out, mostly in Pascagoula.

He said Mississippi Power crews will begin assessing system damage at 6 a.m.

Entergy Mississippi officials said several hundred people were without power in scattered areas of south Mississippi.

Curfews were extended to noon in all three coastal counties — Hancock, Harrison and Jackson. Officials said road conditions were too bad for anyone to be out.

Hancock County Chief Deputy Don Bass said authorities rescued a Bay St. Louis resident from rising water early Wednesday.

Highway 603, the main route to Bay St. Louis and Waveland, was closed at Interstate 10.

"For the most part, we've been lucky, but we've got a long way to go," he said.

Darryl Antoine, a Waveland city worker, spent the night cutting trees off of roads, then checked the city's wells in the morning. He drove to his cousin's house early Wednesday to check on it.

Most of that street was flooded, but the house was rebuilt on stilts after Katrina and didn't appear to have wind damage. Antwoine said his own house was without power, but otherwise fine.

Jerry Beaugez, an assistant with the Bay St. Louis mayor's office has been working with the fire department, and said things have gone relatively well but it's too early to celebrate.

The water was still rising, a tin peeled off a business on Waveland and street signs fluttered in the wind. The storm could pound the area for hours and officials considered closing Highway 603, the main connector from Interstate 10 to Bay St. Louis and Waveland.

"There's not a lot we can do until everything subsides," he said. "As daylight comes, we'll get out and about and assess damages,"

Along low-lying areas along Mississippi's Gulf Coast on Wednesday hurricane-driven water rose several feet in some spots while thousands waited out the storm in shelters. Utilities were reporting more than 15,000 people without power Wednesday and several hundred more scattered around south Mississippi.

Harrison County emergency management director Rupert Lacy said the storm surge coupled with the high tide could lead to more extensive flooding. Lacy said coastal rivers also were beginning to rise from the rainfall.

Hancock County Emergency Management Director Brian Adam said the water stood up to 4 feet deep in many low-lying areas of Hancock County and was still rising while the vast storm system lumbered off the mouth of the Mississippi River.

"It's flooding in quite a bit of places," Adam said, citing reports from Pearlington, Lakeshore and parts of Waveland and Bay St. Louis.

Police waved drivers off U.S. 90, the main beach road in Gulfport, because of flooding. A billboard had torn loose and water stood foot-deep in some areas, knee-deep elsewhere.

Adam said crews successfully rescued three people who had called for help after a houseboat broke loose in Pearlington, near the Louisiana state line but had no major incidents to report immediately.

Hancock County is unusually vulnerable to storm surge because water driven into the Mississippi Sound piles up against the V-shape coast where Louisiana and Mississippi come together. Adam said he wasn't sure if any structures had been damaged. Most buildings destroyed by 2005's Hurricane Katrina in Hancock County were elevated when rebuilt.

American Red Cross spokesman Jay Huffstatler said nearly 2,000 people had entered a total of 33 shelters in Mississippi.

"We've had a great turnout at shelters, people are taking the storm seriously," Huffstatler said.

In Jackson County, Monica Cooper, a spokeswoman for the emergency management agency, was currently reporting 80 flooded roads and reports were increasing "steadily."

She said low lying areas of Moss Point, Gautier and St. Martin were among the hardest hit with flooding. She said the flooding was a combination of heavy rainfall and storm surge.

Cooper said she could not confirm reports that some homes had flooded.

"But with the extent of the flooding I would not be surprised," she said.

In Pass Christian, a coastal community that had been wiped out by hurricanes Camille and Katrina, Mayor Chipper McDermott was optimistic Isaac would not deal a heavy blow.

"It's not too bad, but the whole coast is going to be a mess," he said early Wednesday.

McDermott stood on the porch of the $6 million municipal complex built after Katrina wiped out the city seven years ago today. Its walls are made of 1-foot-thick concrete to withstand hurricane winds.

The mayor lamented that Isaac arrived on the anniversary of Katrina, and said the Hancock County city's recovery had been going well.

As he looked out toward the Gulf of Mexico, pieces of a structure that had stood atop the city's fishing pier washed across the parking lot.

An American flag was flapping wildly in the wind and traffic lights leading into the parking lot flashed as a TV news crew tried to do a live shot.

McDermott said low-lying areas that typically flood were under water. The area has been under a mandatory evacuation. McDermott said many homes there are vacation getaways for New Orleans residents so he thought they were empty as Isaac neared.

In Biloxi, the eastern end of the city, a point that juts into Biloxi Bay where most casinos are located, was being threatened by rising water, authorities had said earlier. They cautioned that the high tide wasn't expected until mid-morning — a critical time as Isaac hung off the nearby coast of southeastern Louisiana.

By dawn, casinos remained mostly dry. Nonetheless, there was water in the bottom floor of Grand Casino's closed-off parking garage. And water lapped around the Palace Casino in East Biloxi.

Tornado warnings had been posted, meanwhile, because of thunderstorms in southern Mississippi. And the back streets of some communities, on higher ground, showed little evidence of Isaac's passage save for some downed tree branches.

Winds rose above 20 mph Tuesday afternoon and stayed there through midnight. A gust of 43 mph was recorded at Gulfport-Biloxi International Airport just after midnight, the worst yet recorded there.

The Mississippi Department of Transportation said beachside U.S. 90, a major thoroughfare, was flooding in several locations in Harrison County, though the agency's functioning traffic cameras showed the road to be passable.

Before Isaac had even reached the Gulf coast, Mississippi Gov. Phil Bryant and other officials were warning residents not to get complacent about Isaac. Authorities had warned of the threat of significant flooding even hundreds of miles inland in coming days.

As Isaac pushed closer to shore Tuesday, bands of rain pelted the Mississippi coast. Harbors were mostly empty, other than disabled boats that couldn't be moved. In Pass Christian, a sail boat had washed aground near the beach and bobbled in the surf. Many houses were boarded up.

The Mississippi Gaming Commission on Tuesday ordered Harrison County's 10 casinos shut on Tuesday, following the Monday closure of Hancock County's two gambling halls. Many businesses were closed, and postal workers wrapped mailboxes in plastic.